Observations on the swelling of cross-linked poly(dimethylsiloxane) networks by solvents

The Flory Huggins Solvent parameter (χ) previously published for a range of solvents and a cross-linked silicone polymer, have been recalculated using the original swelling data, but including a term representing the loss of configurational entropy consequent on crosslinking. From the Shore hardness of the polymer, the Young’s modulus E was calculated. E = 6(C1 + C2), where C1 and C2 are the parameters from the Mooney Rivlin equation for the elastic deformation of an elastomer. Since C1 is related to Mc, the average molecular weight between crosslinks, revised χ values could be calculated for various values of C2/C1. These showed that for good solvents for the silicone polymer, the values published previously were too high.